Anti-lock ball spline assembly

Abstract

A ball spline assembly in which a sleeve is coupled for rotation with and axial movement relative to a shaft by angularly spaced rows of balls which travel in grooved raceways formed in the sleeve and the shaft. A circumferentially extending groove is formed around the shaft near the ends of the raceways therein in order to remove runout from the raceways and thereby prevent the raceways from forcing the balls radially outwardly and locking up the assembly when the shaft is in an extreme axial position relative to the sleeve.

I claim: 
     
       1. A ball spline assembly comprising a shaft having a splined section and a non-splined section, said splined section being formed with a series of angularly spaced and axially extending splines, there being an axially extending raceway of predetermined depth located between each pair of adjacent splines, a sleeve telescoped over said shaft and having angularly spaced and axially extending raceways aligned angularly with the raceways of said shaft, and a row of generally spherical balls located in each pair of angularly aligned raceways to transmit torque between said shaft and said sleeve while reducing friction during relative axial movement of said shaft and said sleeve, said ball spline assembly being characterized by a radially outwardly opening groove extending circumferentially and continuously around said shaft between said splined section and said non-splined section, said groove having sharply radiused ends and a depth at least as great as the depth of the raceways in said shaft and having a bottom adapted to accommodate and contact at least a portion of the end ball in each row when said shaft is in an extreme axial position relative to said sleeve, whereby camming of said balls against said sleeve is substantially prevented. 
     
     
       2. A ball spline assembly as defined in claim 1 in which the axial length of said groove is sufficiently great to accommodate two balls of each row. 
     
     
       3. A ball spline assembly comprising a shaft having a splined section and a non-splined section, said splined section being formed with a series of angularly spaced and axially extending splines having ends proximate to the non-splined section, there being an axially extending raceway of predetermined depth located between each pair of adjacent splines, a sleeve telescoped over said shaft and having a bore formed with angularly spaced and axially extending raceways aligned angularly with the raceways of said shaft, and a row of generally spherical balls located in each pair of angularly aligned raceways to transmit torque between said shaft and said sleeve while reducing friction during relative axial movement of said shaft and said sleeve, said ball spline assembly including run-out area means for substantially preventing camming of the balls against the sleeve, said means being characterized in the provision of a radially outwardly opening and circumferentially continuous groove having sharply radiused ends extending circumferentially around said shaft adjacent the ends of said splines, said groove having a depth at least as great as the depth of the raceways in said shaft and having a bottom receiving and contacting at least a portion of the end ball in each row when said shaft is in an extreme axial position relative to said sleeve, the groove being axially elongated and the bottom of the groove defining a cylindrical surface which extends along a substantial length of the groove.